This subproject is one of many research subprojects utilizing the resources provided by a Center grant funded by NIH/NCRR. The subproject and investigator (PI) may have received primary funding from another NIH source, and thus could be represented in other CRISP entries. The institution listed is for the Center, which is not necessarily the institution for the investigator. We would like to incorporate aspects of our finite difference time-domain (FDTD) modeling of light scattering from cells into the Virtual Tissue Simulator. The FDTD method is an electromagnetic approach that enables accurate modeling of the complete light scattering properties of cells and other tissue components at the sub-micron scale. Although FDTD simulations are computationally demanding, it should be possible to create a database of scattering cross-sections and phase functions for a wide range of cellular structures and compositions that could be incorporated into macroscopic Monte Carlo methods. Such an approach would enable users to specify cellular and sub-cellular features of tissue components and then investigate how changes in the microscopic parameters translate to macroscopic optical changes.